1. Field of the Invention
This invention relates to filters for filtering fluids such as engine oil, coolant, fuel, hydraulic or transmission fluid.
2. Description of Related Art
Fluid filters are used to remove contaminants from fluid, such as engine oil. Internal combustion engines use oil to lubricate bearings and reduce friction. This oil is circulated through the engine and carries contaminants such as metal particles, carbon particles and dirt which may cause harm to the engine. In order to effectively lubricate the engine, engine oil is passed through a filter to remove the contaminants before the oil is recirculated into the engine. The typical oil filter is attached to an internal combustion engine at the oil filter receptacle.
Engine oil passes through a discharge opening in the oil filter receptacle, into a fluid filter and then into the engine lubrication system through an oil inlet pipe. A filter element in the fluid filter removes contaminates from the oil before it reenters the engine through the oil inlet pipe. Because of the dynamic nature of this process, oil filters must be sealed to protect from oil leaking into the atmosphere.
Oil filters have traditionally been of a disposable type creating a great environmental concern. Used oil filters are disposed of in landfills or by incinerating. Recent improvements in the art have separated the filter elements from the filter canister allowing users to dispose of only the filter element and thus reducing the quantity of waste material. However, a large volume of waste is still generated by disposing of the filter element.
For both reusable and disposable filter assemblies, there is a need for a fluid filter having a pressure relief valve to allow fluid to continue to flow in the event the filter element becomes clogged whereby the valve provides ease of assembly, reduced cost, and reduced valve size.